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D Bosco

Publications and source records attributed to D Bosco.

At least 91 records · Page 5Linked to original sources
PubMed1989

Effects of n-alcohols on junctional coupling and amylase secretion of pancreatic acinar cells.

We have tested the effects of alcohols differing by their alkyl chain length on the membrane channels and amylase secretion of rat pancreatic acinar cells. In intact acini, alcohols with a chain of seven, eight, or nine carbons (C-7, C-8, and C-9) induced dye uncoupling and increased basal amylase release. These effects were readily reversible after alcohol removal. By contrast, an alcohol with a chain of 15 carbons (C-15) and several alcohols with chains of fewer than six carbons (C-2, C-4, and C-6) did not uncouple acinar cells and had no effects of amylase secretion. Neither did alkanes and oxidized derivatives of C-7 and C-8 alcohols did not affect dye coupling. Double patch-clamp experiments on pairs of acinar cells, under conditions of strong cytosolic Ca2+ and pH buffering, showed that C-7, C-8, and C-9 alcohols blocked completely and reversibly the electrical conductance of junctional channels. Furthermore, studies of single voltage-clamped acinar cells revealed that the uncoupling alcohols did not affect the resting nonjunctional membrane conductances. Thus the alcohols that did not affect acinar cells coupling did not affect amylase secretion, whereas the alcohols that caused uncoupling increased secretion. The latter effect was not mediated by changes in the conductance of nonjunctional membrane, cytosolic Ca2+, and pH and, as revealed by an immunological hemolytic plaque assay for amylase, had a time course consistent with the rapid (within 1 min) inhibition of coupling. These data provide new support for the view that the regulation of cell-to-cell communications is correlated with that of digestive enzyme secretion.

Alcohols↗
PubMed1989

Homologous but not heterologous contact increases the insulin secretion of individual pancreatic B-cells.

To assess whether and how specifically contact influences the functioning of differentiated cells, we have studied the secretion of adult pancreatic B-cells as a function of aggregation to either homologous B-cells or other heterologous endocrine islet cell types, all present in a mixed cell suspension. Using an immunological plaque assay for insulin, we have quantitated the proportion of single and aggregated B-cells inducing the formation of a hemolytic plaque (a reflection of the size of the secreting cell population) and the area of these plaques (a reflection of the hormonal output of individual cells or aggregates) after a 30-min stimulation by 16.7 mM glucose. By taking into account the number of B-cells within the aggregates, we have calculated from these data the insulin output on a per B-cell basis. We show here that the homologous contact between companion B-cells promotes the recruitment of secreting B-cells and increases their individual secretion of insulin twofold over that of single B-cells. By contrast, heterologous B- to non-B-cell contact was not effective in enhancing the recruitment of secreting B-cells and in promoting their individual secretion. These findings show that a highly differentiated cell function, such as insulin secretion, is controlled specifically by homologous cell to cell contacts.

Animals↗
PubMed1989

The use of pulse oximetry in the immediate recovery phase following dental extractions under general anesthesia in children.

Over the past decade, an array of monitoring devices have been developed to continuously assess patient oxygenation. While actual tissue oxygenation is the most desirable measurement, the pulse oximeter offers a non-invasive method of measuring oxygenation of arterial blood. In this study, the arterial oxygen saturation (SaO2) of children presenting for oral surgical procedures under general anesthesia was continuously monitored. We were particularly interested in the saturation during the period from termination of anesthesia until arrival in the recovery room, a potentially critical 2-3 minutes. This study showed that 22.5 per cent of children significantly desaturated (SaO2 less than 90 per cent) during this period - a figure which is in complete agreement with several similar studies done recently. This desaturation preceded not only hemodynamic changes, but frequently changes in tissue and blood colour as well. The authors conclude that children should receive supplemental oxygen in the immediate recovery phase following general anesthesia.

Adolescent↗
PubMed1988

Visualization of amylase secretion from individual pancreatic acini.

To assess the secretion of individual rat pancreatic acini, we developed a reverse hemolytic plaque assay that allows for a direct visualization of amylase release. This release was detected around secreting cells by the presence of hemolytic plaques that resulted from the complement-mediated lysis of red blood cells bearing amylase-antiamylase complexes bound to protein A. Controls showed that these plaques reflected specifically the active secretion of amylase. Quantitation of hemolytic plaques showed that after a 30-min incubation approximately 50% of the acini secreted under basal conditions. Stimulation of amylase release by increasing concentrations of carbamylcholine resulted in a dose-dependent recruitment of secreting acini as well as in a time-dependent enhancement in the response of individual acini. Under all conditions, the wide distribution of hemolytic plaque sizes indicated large differences in the secretory output of individual acini. Thus, using a new method to directly visualize and quantitate amylase secretion, we have provided evidence for a functional heterogeneity of pancreatic acini.

Amylases↗
PubMed1987

Gap junctional coupling modulates secretion of exocrine pancreas.

Dispersed pancreatic acini were studied to assess the function of junctional coupling between adult secretory cells. Nonstimulated control cells were extensively coupled to their neighbors throughout each acinus. Addition of heptanol caused their uncoupling and increased their basal amylase release. Neurotensin, secretin, and vasoactive intestinal peptide (VIP) stimulated amylase secretion without uncoupling acinar cells. Heptanol rapidly and markedly uncoupled the neurotensin-, secretin-, and VIP-stimulated acinar cells and increased their amylase secretion in an additive manner. By contrast, the secretory response to carbamoylcholine (carbachol), a secretagogue that, alone, uncoupled acinar cells, was not affected by heptanol. Basal as well as neurotensin-, secretin-, and VIP-stimulated output returned to the lower control values following removal of heptanol and recovery of normal coupling. The data provide evidence that blockage of gap junctional coupling increases the basal secretion of exocrine pancreas as well as the response of the gland to a variety of secretagogues.

Alcohols↗
PubMed1987

Plasminogen activator and mouse spermatozoa: urokinase synthesis in the male genital tract and binding of the enzyme to the sperm cell surface.

When ejaculated mouse spermatozoa were embedded in a plasminogen-containing insoluble protein substrate, a zone of proteolysis developed progressively, centered around the sperm head region. Lysis did not occur in absence of plasminogen or in presence of antibodies against the urokinase-type plasminogen activator (u-PA). Zymographic and immunological analyses confirmed the presence of u-PA in extracts of ejaculated mouse spermatozoa. In contrast, the u-PA activity of sperm cells obtained from testis or from vas deferens was low, although these cells were able to bind added murine u-PA. The sites of u-PA synthesis were identified by measuring u-PA activity and u-PA mRNA content in protein extracts and in total RNA preparations of various portions of the male genital tract. The highest levels of u-PA activity and of u-PA mRNA were found in vas deferens and seminal vesicles. The cells that synthesize u-PA were localized by hybridizing frozen sections of various portions of the genital tract to a u-PA cRNA probe. In all tissues examined, u-PA mRNA was predominantly located in the epithelial layer, and the strongest signal was observed over that of the vas deferens. Hence, the u-PA associated with ejaculated sperm cells is probably acquired from genital tract secretions. Sperm-bound u-PA may participate in the proteolytic events that accompany capacitation and fertilization.

Animals↗
PubMedDate not supplied

[Diabetes Type I therapy through transplantation].

Diabetes is one of the most common chronic diseases in our society. While insulin treatment for diabetes type I could delay and reduce the incidence of diabetic complications, it is associated with an increased risk of severe hypoglycemia. To restore physiologic insulin metabolism, transplantation of insulin producing cells (pancreatic Beta cells) represent the sole available therapy. It could be done either through pancreas or islet of Langerhans transplantation. In this paper, we review actual knowledge regarding these two types of transplantations.

Diabetes Mellitus, Type 1↗
PubMedDate not supplied

Phylogenetic disparity influences the predominance of direct over indirect pathway of antigen presentation in islet xenotransplantation.

BACKGROUND: Cellular immunity plays a major role in rejection of xenografted islets. Depending on the phylogenetical disparity, direct or indirect antigen presentation is predominant. The aim of this study was to analyze in vitro the predominance of direct or indirect presentation, and in vivo the effect of macrophage depletion on concordant and discordant islet xenograft survival. MATERIALS AND METHODS: In vitro, we performed mouse antirat and mouse antihuman mixed lymphocyte reactions (MLR) after depletion of responder or stimulator antigen-presenting cells. In vivo, streptozotocin-induced diabetic C57BL/6 mice were treated by gadolinium chloride to deplete macrophages and rat or human islets were transplanted under the kidney capsule. Islet function was followed by glycemia and xenografts were analyzed at regular intervals for histology. RESULTS: Mouse antirat MLR showed a predominant direct antigen presentation pathway, whereas in mouse antihuman MLR, direct and indirect pathways were similarly involved. Survival of rat islets was not modified by GdCl therapy. In contrast, survival of human islets was significantly prolonged in GdCl-treated mice. Macrophage infiltration was decreased in concordant and discordant GdCl-treated xenografts at day 4, compared to controls. At day 15, macrophage infiltration was similar in all groups. DISCUSSION: Our results indicate that direct antigen presentation is dominant in rejection of concordant islet xenografts and cannot be influenced by host macrophage depletion. Both direct and indirect antigen presentation are involved in rejection of discordant xenogeneic islets. Macrophage depletion or inhibition should be considered as therapeutic tool for discordant islet xenotransplantation.

Animals↗
PubMedDate not supplied

Role of CD40-CD154 pathway in the rejection of concordant and discordant xenogeneic islets.

BACKGROUND: Costimulatory blockade has been shown to allow long-term survival of xenogeneic islets. The aim of the present study was to evaluate the role of recipient CD40 and CD154 in the rejection process of concordant and discordant islet xenotransplantation (Tx). METHODS: Diabetic C57BL/6 mice, CD40- or CD154 knockout (KO) mice were transplanted with either concordant rat or discordant human islets. EXPERIMENTAL DESIGN: group 1, control (ie, C57BL/6 mice received islet Tx without therapy); group 2, C57BL/6 mice received islet Tx with anti-CD154 monoclonal Ab (mAb) therapy; group 3, CD40 KO mice; and group 4, CD154 KO mice were used as recipients without therapy. Mouse anti-rat mixed lymphocyte reactions (MLR) were performed using mouse splenocytes obtained from animals transplanted with rat islets in groups 1 to 4. RESULTS: In group 2, short-term anti-CD154 mAb therapy significantly prolonged rat-to-mouse and human-to-mouse xenograft survival, compared to controls. In CD40-KO and CD154-KO recipients, survival of concordant or discordant islets was not prolonged significantly compared to control groups. Mouse anti-donor rat cellular responses were reduced approximately 50% in group 2 but remained unmodified in groups 3 and 4, when compared to group 1. CONCLUSIONS: Improved graft survival and reduced MLR responses against donor cells in vitro among the anti-CD154 mAb-treated mice could be explained by specific targeting of activated T cells with subsequent inactivation by anergy and/or elimination by apoptosis, or complement- or cellular-mediated mechanisms. Rejection of xenografts and strong MLR responses against donor cells in vitro in CD40 or CD154 KO animals is possible through efficient activation of alternate pathways of costimulation.

Animals↗
PubMedDate not supplied

Treatment of fulminant liver failure by transplantation of microencapsulated primary or immortalized xenogeneic hepatocytes.

BACKGROUND: The aim of this study was to evaluate the in vitro and in vivo function of hepatocytes after immortalization, cryopreservation, encapsulation, and xenotransplantation into mice with fulminant liver failure (FLF). METHODS: Rat and human hepatocytes were isolated by collagenase digestion. Human hepatocytes were immortalized using lentiviral vectors. Rat and immortalized human hepatocytes (IHH) were encapsulated in 400 microm of alginate-poly-L-lysine (PLL; Sigma, Buchs, Switzerland)-alginate membranes and cryopreserved using a computerized device. In vitro, encapsulated hepatocytes (cryopreserved or noncryopreserved) were cultured; albumin secretion was measured by enzyme-linked immunosorbent assay. Microencapsulated (cryopreserved or noncryopreserved) hepatocytes were transplanted intraperitoneally to mice with FLF: group 1 (n = 10) transplantation of empty capsules; group 2 (n = 12) transplantation of free primary rat hepatocytes; group 3 (n = 12) transplantation of cryopreserved encapsulated rat hepatocytes; group 4 (n = 10) transplantation of encapsulated rat hepatocytes; group 5 (n = 9) transplantation of cryopreserved encapsulated IHH; group 6 (n = 10) transplantation of encapsulated IHH. RESULTS: Compared with free primary hepatocytes, cryopreserved or noncryopreserved encapsulated rodent hepatocytes showed similar levels of continuous in vitro albumin secretion over 1 week. Cryopreserved or noncryopreserved encapsulated IHH showed minimal albumin secretion compared with free primary human hepatocytes. Fulminant liver failure, produced by a combination of acetaminophen and 30% hepatectomy, resulted in a 20% to 30% host survival. In groups 1 and 2, survival was unmodified, compared with untreated mice. For groups 3 and 4, transplantation of cryopreserved or noncryopreserved encapsulated rat hepatocytes significantly increased survival rates to 66% and 80%, respectively (P < .01). For groups 5 and 6, transplantation of cryopreserved or noncryopreserved encapsulated IHH improved host survival to 50% and 55%, respectively (P < .05). CONCLUSIONS: Primary rodent hepatocytes maintained synthetic functions after encapsulation and cryopreservation. Immortalized human hepatocytes showed minimal albumin secretion in the absence of encapsulation and cryopreservation, suggesting that hepatocytes lose some specific functions after immortalization. After induction of FLF in mice, intraperitoneal transplantation of encapsulated (primary or immortalized, cryopreserved or noncryopreserved) xenogeneic hepatocytes significantly improved survival. These results indicate that naive and genetically modified hepatocytes can be successfully encapsulated, stored by cryopreservation, and transplanted into xenogeneic recipients with FLF to sustain liver metabolic functions.

Animals↗
PubMedDate not supplied

Correlations between protein kinase C zeta signaling and morphological modifications during rat heart development and aging.

From birth to aging the heart undergoes functional changes reflecting biochemical and ultrastructural modifications which imply apoptosis. This is a physiological process resulting from genetic programs closely associated with development and aging. During development apoptosis eliminates redundant cells leading to heart remodeling, while during aging it eliminates damaged or exhausted cells. In the present paper we analyze some molecular mechanisms involved with heart morphological modifications, especially in the neonatal heart which displays different features in the subendocardial and myocardial area. The high number of subendocardial apoptotic cells and the inverted ratio of Bcl-2/Bax molecule expression in the two heart compartments led us to hypothesize a different metabolism in the myocardium as compared with subendocardium. Moreover, we propose that PKC zeta may mediate this different response by activating Nf-kB pathway and by maintaining the balance between hypertrophic growth and apoptosis involved with remodeling of neonatal heart. Further, we underline that in the aged heart, where this pathway is not activated, such balance is not maintained.

Aging↗
PubMedDate not supplied

Caspase-3 is dually regulated by apoptogenic factors mitochondrial release and by SAPK/JNK metabolic pathway in leukemic cells exposed to etoposide-ionizing radiation combined treatment.

Ionizing radiation induces a series of multiple intracellular events which can lead to activation of caspases, cytoplasmic proteases involved in the occurrence of apoptosis. The response of leukemic cells to ionizing radiation is amplified when they have been pre-treated with the anticancer drug etoposide, therefore the aim of this work has been to establish the lowest etoposide concentration combined with the lowest ionizing radiation dose to obtain the best antineoplastic response. Two leukemic cell lines, HL-60 and Jurkat, employed in this study demonstrated different sensitivities to ionizing radiation and to etoposide treatment, with Jurkat T cells requiring a higher dose (1 microM) to display cell cycle perturbation and apoptotic DNA damage similar to those seen in HL-60. We hypothesize that this kind of response could be mediated by mitochondrial release of apoptogenic factors and by SAPK/JNK metabolic pathway activation, both leading to caspase-3 cleavage. All in all these results provide insight into the sensitivity or resistance of leukemic cells to antineoplastic agents and identify molecular targets for rational therapeutic intervention strategies.

Antineoplastic Agents, Phytogenic↗
PubMedDate not supplied

Detection of Chlamydia pneumoniae in atherosclerotic coronary arteries.

Chlamydia pneumoniae has recently been associated with the development of coronary heart diseases by sero-epidemiological studies and by direct detection of the organism in atherosclerotic tissues. The aim of our study was to employ a semi-nested PCR approach to investigate the presence of C. pneumoniae in both normal and atherosclerotic coronary arteries of humans obtained at autopsy. Moreover, we have evaluated the role of infection with C. pneumoniae in relation to the extent of coronary atherosclerosis. One hundred and eighty coronary artery specimens were collected at autopsy from 60 consecutive subjects (three arterial segments from each subject). Atherosclerosis in each arterial segment was graded histologically by the Stary classification. Thirty normal coronary arteries were also taken at autopsy as control. PCR results evidenced the presence of C. pneumoniae DNA in atherosclerotic coronary arteries in 19 (31.7%) of 60 subjects examined, while none of the 30 subjects with non-atherosclerotic tissues was positive (p=0.001). Moreover, of the 180 atherosclerotic specimens examined, C. pneumoniae DNA was detected in 3.4% (2/59) of mild atherosclerotic lesions, and in 14.0% (17/121) of advanced atherosclerotic lesions (p=0.05). Our results demonstrate that the presence of C. pneumoniae DNA may be associated with the severity of coronary atherosclerosis.

Adult↗
PubMedDate not supplied

Protein kinase C zeta regulation of hypertrophic and apoptotic events occurring during rat neonatal heart development and growth.

The development and growth of the rat heart implies hyperplasia, which stops at birth, and hypertrophy, allowing cardiac mass to grow in response to programmed genetic events along with to haemodynamic overload. Moreover, hypertrophy is accomplished to apoptosis which controls the final number of myocardial cells, deletes vestigial structures, and takes part in remodelling the organ. Since at the basis of all these processes, which lead to the complete development of the heart, the activation of specific signalling pathways underlies, attention has been addressed to the role played in vivo by Protein Kinase C zeta (PKC zeta) in regulating NF-kB signalling system and intrinsic mitochondrial apoptotic route at days 1, 4, 10 and 22 of rat life. In fact, a role has been assigned to PKC zeta in indirectly phosphorylating IKBa, which peaks between 10 and 22 days, through a IKK determining, in turn, NF-kB activation, concomitantly to cytochrome c/Apaf 1 co-localization in the cytoplasm and caspase-9/caspase-3 activation, which leads to the occurrence of apoptosis. Thus a key role for PKC zeta in regulating the hypertrophic and apoptotic events leading to establishment of complete function in rat neonatal heart is here suggested.

Animals↗
PubMedDate not supplied

[Differential diagnostic problems between nodular fasciitis and soft-tissue sarcomas. A review of the literature and a case report].

After a review of literature and the report of a case with intrathoracic location, the authors consider present criteria for a correct diagnosis of low grade soft tissue sarcoma, when the possibility of nodular fasciitis is under evaluation. Nodular fasciitis is a benign pathology up to day not well characterised from the clinical and pathological point of view. The authors conclude that differential diagnosis between low grade soft tissue sarcoma and nodular fasciitis is frequently possible only on the basis of clinical course evaluation; otherwise the management may be inadequate.

Adult↗
PubMedDate not supplied

Altered expression of hMSH2 in sporadic colorectal cancer, surrounding mucosa and at distant colonic mucosa.

BACKGROUND: Mismatch repair gene hMSH2 is involved in correction of mispairing during replication and its mutation is associated both with microsatellite instability and with hereditary colorectal cancer. We evaluated its involvement in sporadic colorectal cancer tumorigenesis too. MATERIALS AND METHODS: The protein expression pattern of hMSH2 was evaluated on 29 cases of resected sporadic adenocarcinoma using an immunohistochemical approach. RESULTS: In 14 cases, lack of hMSH2 protein expression was observed in adenocarcinoma and in peritumoral mucosa. In 12 patients, hMSH2 resulted in strong expression in the tumour as well as in the surrounding mucosa and at distant mucosa. In three cases, hMSH2 protein expression in tumoral, adjacent and at distance normal mucosa resulted negative. CONCLUSION: Repair genes could play an important role in tumour progression and in sporadic colorectal cancer. Detection of protein expression by immunohistochemistry may be a method to select tumours for successive genetic investigations.

Adenocarcinoma↗